I am trying to think of it in terms like you say... a transfer from another state, or abroad, etc., would they really make that child repeat k, or 3rd grade, or whatever grade they just finished? Hope not.
Just to warn you, I used that tactic once and failed. DS was accelerated to 2nd in our local district. The previous spring in kindy, he had done 3/4ths of the 2nd grade math curriculum, so we were surprised when they had him doing the exact same curriculum, from the beginning of the book, when he started 2nd. While trying to convince the school that he should not have to do 2nd grade math all over again, we posed the following question: "So if there were 2 classes of second graders, and Mrs. A's class made it all the way through the book, but Mrs. B's class only made it 3/4ths of the way through, but all the kids were promoted to 3rd, are you telling us that you would have all of Mrs. B's class take the entire 2nd grade math over again?" To which we received the response, "Yes." Sometimes arguments just don't work, and it's not because they weren't good arguments. From this experience, I learned that it is unwise to ask such questions with a tone suggesting you seriously cannot believe they would answer yes, but rather try to do more of a Columbo-type ignorant tone...